1. Field of the Invention
The present invention relates to a discharge arrangement for discharging materials from storage. More particularly, the present invention relates to a door mechanism allowing selective discharge of materials from railroad hopper cars. Most particularly, the present invention relates to a conversion or new construction for hopper cars having horizontally oriented discharge openings.
2. Description of the Prior Art
Railroad hopper cars are used to transport many types of material including, but not limited to, coal, grain, crushed stone and other loose bulk materials. It is generally customary to fully discharge material from hopper cars into an opening between the railroad tracks by a continuous flow when the hopper doors have been opened.
The use of a discharge arrangement to control the discharge of materials through a bottom outlet in a railroad hopper car is well known. Known discharge arrangements or gate assemblies are disclosed for example in U.S. Pat. Nos. 3,902,434; 4,250,814; and 5,086,709.
The arrangement in the ('434) patent shows a pneumatic motor actuated mechanism to open railroad hopper car doors in which a grooved central member moves vertically between the upper ends of two pivoting swing arms to pull them together or push them apart so as to open or close doors fastened to the lower ends of the swing arms.
The discharge arrangement of the ('814) patent shows a pair of relatively light weight doors which are opened and closed sequentially from an overlapping position by means of a longitudinally extending actuating mechanism moveably supported on the under frame of the car.
The discharge arrangement in the ('709) patent shows a sliding gate structure for controlling discharge of material from openings defined at a lower end of a railroad hopper car. The openings are covered by a pair of gates which linearly move in guide tracks to discharge the material inside or outside of the rails, depending upon which gate is operated.
There have existed problems in the prior art with sliding gate assemblies of the horizontal type such as currently are in wide use in hopper cars primarily used to haul grain. These hopper cars have sliding gates similar to the type shown in the ('709) patent, but they are mounted horizontally, and slide horizontally to close horizontal discharge openings. When used with light weight products such as grain, these gates operate generally satisfactory. However, as pressure developed to use all rail cars more efficiently, it has been desired to have the capability of using the grain hopper cars with other materials such as coal, crushed stones, loose bulk materials, and aggregates for which the car was not originally designed.
It is when gate assemblies originally intended for grain are used with such materials that problems develop. Due to the courser and more abrasive nature of such materials, the gates become difficult to slide. Also when used for coal, aggregates, etc. loose particles of such materials are trapped in the gate slides, and make the operation of the mechanism difficult and erratic. It was in an attempt to solve these problems in existing grain hopper cars that led to the development of the present invention. The solution to the problems in the art have been so successful that the construction disclosed is contemplated as a conversion or original construction for all type of hopper cars.